1. Technical Field
The invention disclosed broadly relates to data processing systems and methods and more particularly relates to a data processing method for the efficient simulation of a data communications network operating with a window-based protocol.
2. Background Information
Window protocols have been successfully used for multiple purposes in computer networks. Often, they are found at several network architecture layers. They provide a means for flow control and are at the heart of any network congestion control mechanism. Typical window protocols are found in IBM's System Network Architecture which is explained, for example, in the book by Anura Guruge, SNA--Theory in Practice, Pergamon Infotech Ltd., 1984. Another window protocol system can be found in DECnet which is described, for example, in the article by Raj K. Jain, "A Timeout Based Congestion Control Scheme for Window Flow Controlled Networks," IEEE Journal on Selected Areas in Communications, Vol. SAC-4, No. 7, October 1986. Window protocols allow control of the amount of data in transit between two users of the protocol. As a flow control mechanism they prevent a fast sender from overwhelming a slow receiver. The prior art approach to the analysis of window protocols has been limited to queuing theory or by simulation. Formal queuing theory is used in the analysis of computer network behavior. An example of this is described by Leonard Kleinrock, "Queuing Systems," Vol. 2, Computer Applications, New York: Wiley - Interscience, 1976.
Since queuing theory analysis has problems characterizing the dynamic behavior of a network, simulation methods have been applied. Typically, simulations are performed to validate analytic models or investigate the operational details of a specific mechanism. However, considerable effort is involved in building and running any simulator. The use of a benchmark that specifies system topology, hardware behavior and trial workloads requires development. Frequently, shortcuts are taken at the expense of accuracy. Validation of a simulation model and the proper choice of a benchmark to evaluate window protocol behavior appear to be open problems.